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/**
 * @file mixer_multirotor.cpp
 *
 * Multi-rotor mixers.
 */

#include <nuttx/config.h>

#include <sys/types.h>
#include <stdint.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <poll.h>
#include <errno.h>
#include <stdio.h>
#include <math.h>
#include <unistd.h>
#include <math.h>

#include "mixer.h"

#define		CW		(-1.0f)
#define		CCW		(1.0f)

namespace
{

/*
 * These tables automatically generated by multi_tables - do not edit.
 */
const MultirotorMixer::Rotor _config_quad_x[] = {
	{ -0.707107,  0.707107, -1.00 },
	{  0.707107, -0.707107, -1.00 },
	{  0.707107,  0.707107,  1.00 },
	{ -0.707107, -0.707107,  1.00 },
};
const MultirotorMixer::Rotor _config_quad_plus[] = {
	{ -1.000000,  0.000000, -1.00 },
	{  1.000000,  0.000000, -1.00 },
	{  0.000000,  1.000000,  1.00 },
	{ -0.000000, -1.000000,  1.00 },
};
const MultirotorMixer::Rotor _config_hex_x[] = {
	{ -1.000000,  0.000000,  1.00 },
	{  1.000000,  0.000000, -1.00 },
	{  0.500000,  0.866025,  1.00 },
	{ -0.500000, -0.866025, -1.00 },
	{ -0.500000,  0.866025, -1.00 },
	{  0.500000, -0.866025,  1.00 },
};
const MultirotorMixer::Rotor _config_hex_plus[] = {
	{  0.000000,  1.000000,  1.00 },
	{ -0.000000, -1.000000, -1.00 },
	{  0.866025, -0.500000,  1.00 },
	{ -0.866025,  0.500000, -1.00 },
	{  0.866025,  0.500000, -1.00 },
	{ -0.866025, -0.500000,  1.00 },
};
const MultirotorMixer::Rotor _config_octa_x[] = {
	{ -0.382683,  0.923880,  1.00 },
	{  0.382683, -0.923880,  1.00 },
	{ -0.923880,  0.382683, -1.00 },
	{ -0.382683, -0.923880, -1.00 },
	{  0.382683,  0.923880, -1.00 },
	{  0.923880, -0.382683, -1.00 },
	{  0.923880,  0.382683,  1.00 },
	{ -0.923880, -0.382683,  1.00 },
};
const MultirotorMixer::Rotor _config_octa_plus[] = {
	{  0.000000,  1.000000,  1.00 },
	{ -0.000000, -1.000000,  1.00 },
	{ -0.707107,  0.707107, -1.00 },
	{ -0.707107, -0.707107, -1.00 },
	{  0.707107,  0.707107, -1.00 },
	{  0.707107, -0.707107, -1.00 },
	{  1.000000,  0.000000,  1.00 },
	{ -1.000000,  0.000000,  1.00 },
};
const MultirotorMixer::Rotor *_config_index[MultirotorMixer::Geometry::MAX_GEOMETRY] = {
	&_config_quad_x[0],
	&_config_quad_plus[0],
	&_config_hex_x[0],
	&_config_hex_plus[0],
	&_config_octa_x[0],
	&_config_octa_plus[0],
};
const unsigned _config_rotor_count[MultirotorMixer::Geometry::MAX_GEOMETRY] = {
	4, /* quad_x */
	4, /* quad_plus */
	6, /* hex_x */
	6, /* hex_plus */
	8, /* octa_x */
	8, /* octa_plus */
};

}

MultirotorMixer::MultirotorMixer(ControlCallback control_cb,
				 uintptr_t cb_handle,
				 Geometry geometry,
				 float roll_scale,
				 float pitch_scale,
				 float yaw_scale,
				 float deadband) :
	Mixer(control_cb, cb_handle),
	_roll_scale(roll_scale),
	_pitch_scale(pitch_scale),
	_yaw_scale(yaw_scale),
	_deadband(-1.0f + deadband),	/* shift to output range here to avoid runtime calculation */
	_rotor_count(_config_rotor_count[geometry]),
	_rotors(_config_index[geometry])
{
}

MultirotorMixer::~MultirotorMixer()
{
}

unsigned
MultirotorMixer::mix(float *outputs, unsigned space)
{
	float		roll    = get_control(0, 0) * _roll_scale;
	float		pitch   = get_control(0, 1) * _pitch_scale;
	float		yaw     = get_control(0, 2) * _yaw_scale;
	float		thrust  = get_control(0, 3);
	float		max     = 0.0f;
	float		fixup_scale;

	/* use an output factor to prevent too strong control signals at low throttle */
	float min_thrust = 0.05f;
	float max_thrust = 1.0f;
	float startpoint_full_control = 0.40f;
	float output_factor;

	/* keep roll, pitch and yaw control to 0 below min thrust */
	if (thrust <= min_thrust) {
		output_factor = 0.0f;
	/* linearly increase the output factor from 0 to 1 between min_thrust and startpoint_full_control */
	} else if (thrust < startpoint_full_control && thrust > min_thrust) {
		output_factor = (thrust/max_thrust)/(startpoint_full_control-min_thrust);
	/* and then stay at full control */
	} else {
		output_factor = max_thrust;
	}

	roll *= output_factor;
	pitch *= output_factor;
	yaw *= output_factor;


	/* perform initial mix pass yielding un-bounded outputs */
	for (unsigned i = 0; i < _rotor_count; i++) {
		float tmp = roll  * _rotors[i].roll_scale +
			    pitch * _rotors[i].pitch_scale +
			    yaw   * _rotors[i].yaw_scale +
			    thrust;

		if (tmp > max)
			max = tmp;

		outputs[i] = tmp;
	}

	/* scale values into the -1.0 - 1.0 range */
	if (max > 1.0f) {
		fixup_scale = 2.0f / max;

	} else {
		fixup_scale = 2.0f;
	}

	for (unsigned i = 0; i < _rotor_count; i++)
		outputs[i] = -1.0f + (outputs[i] * fixup_scale);

	/* ensure outputs are out of the deadband */
	for (unsigned i = 0; i < _rotor_count; i++)
		if (outputs[i] < _deadband)
			outputs[i] = _deadband;

	return 0;
}

void
MultirotorMixer::groups_required(uint32_t &groups)
{
	/* XXX for now, hardcoded to indexes 0-3 in control group zero */
	groups |= (1 << 0);
}

